- 2 cups kumquats, stemmed, quartered, seeded; plus 2 kumquats, sliced thinly
- Nonstick vegetable oil spray
- 3 cups all purpose flour
- 2 teaspoons instant iced tea powder (optional)
- 1 1/2 teaspoons baking powder
- 1 teaspoon baking soda
- 1/2 teaspoon ground cardamom
- 2 teaspoons kosher salt, divided
- 1 1/4 cups sugar
- 3/4 cup plus 1 tablespoon corn oil
- 3 large eggs
- 2 teaspoons vanilla extract
- 1 8-ounce can crushed pineapple in its own juice
- 1 cup walnuts, toasted, chopped
- 1/4 cup (1/2 stick) unsalted butter, room temperature
- 3 cups powdered sugar
- 1 tablespoon fresh lemon juice
- Place quartered kumquats in processor; puree 3 minutes. Measure 1/3 cup puree for glaze; set aside.
- Position rack in center of oven; preheat to 350°F. Spray two 8 1/2×4 1/2×2 1/2-inch metal loaf pans with nonstick spray. Combine flour, tea powder (if desired), baking powder, baking soda, cardamom, and 1 1/2 teaspoons salt in medium bowl; whisk to blend. Using electric mixer, blend 1 1/4 cups sugar and oil in large bowl. Beat in eggs, 1 at a time, then vanilla, 2/3 cup kumquat puree, and pineapple with juice. Gradually add dry ingredients, beating just until blended. Fold in walnuts. Divide batter between prepared pans.
- Bake cakes until tester inserted into center comes out clean, about 1 hour. Cool 5 minutes in pans on rack. Turn cakes out; place top side up on rack and cool.
- Place reserved 1/3 cup puree in large bowl. Whisk in butter, powdered sugar, lemon juice, and 1/2 teaspoon salt. Spread glaze over cakes, dividing equally. Top with kumquat slices. Let stand until icing sets. (Can be made 1 day ahead. Wrap in foil; store at room temperature.)